atm: idt77252: Fix set-but-unused variables.

Two cases here:

1) idt77252_rx_raw() really does not make any use of the
   extracted PTI field of the atm header.

2) idt77252_collect_stat() only uses the register values
   in code which has been compiled out by a "NOTDEF" cpp
   test for more than 10 years.  Just kill this NOTDEF
   code entirely, but keep the register reads in case
   they have side effects.

Signed-off-by: David S. Miller <davem@davemloft.net>